摘要:

The Syrian hamster is a suitable animal model for the study of pancreatic neoplasms of ductal origin. Therefore, the present study was performed to obtain basic information on the pancreas of this species in neonatal life and during the aging process. Scanning electron-microscopic (SEM) examination showed that the islets of Langerhans could not be seen in the pancreas at day 15 of gestation or shortly after delivery, but developed during the first 14 postnatal days and doubled their size by 4 weeks after birth. In hamsters over 1 year of age, the islets of Langerhans attain a diameter of approximately 300 µm. Cells of the acini in the fetal pancreas already contain zymogen-like granules, their final size is reached by 28 days postpartum. Age does not markedly affect the epithelial cell height of the pancreatic ducts. Small ducts are lined with cuboidal large ducts with a columnar epithelium. The epithelial height correlates with luminal size which increases with age. The luminal surface of the ductal epithelium shows varying forms and density of microvilli, and usually a single, centrally located cilium. Mucus-producing cells, identified by droplets which protrude onto the cell surface, are first seen in the common duct of 4-week-old hamsters and are prominent in adult animals

ISSN:1422-6405    

DOI:10.1159/000145236

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The author’s ‘Variation in morphology of teeth’ (1978) reported findings in extracted teeth, part of which involved intensive study of deformity in maxillary third molars. This suggests that abnormal developmental relations could have obstructed or perverted the tooth’s potential morphology. Some third molar characters, seen also in well-developed palates and in various ethnic groups, may reflect a certain combination of normal variables. These latter teeth have hitherto aroused little comment other than their description as ‘co

ISSN:1422-6405    

DOI:10.1159/000145237

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

There is a marked evolution in the ultrastructure of the chicken pineal gland after hatching. The typical large follicular cavities tha tare visible just after hatching disappear with age, giving the pineal a large number of small-caliber cavities which are practically filled by the prolongations of the pinealocytes. This gives the organ an apparently solid aspect. There are still two large cell types in the follicular wall: the A and B pinealocytes, with the B type being considerably more abundant.

ISSN:1422-6405    

DOI:10.1159/000145238

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

An ultrastructural study of the boundary tissue of the seminiferous tubule of the camel reveals that it consists of three lamellae; inner fibrous, inner cellular and outer cellular. The inner lamella is subdivided into two homogeneous layers enclosing a third one that contains collagenous fibres and fine filaments. The inner cellular lamella consists of several layers of myoid cells; each layer is separated from the adjacent layer by homogeneous material and varying amounts of collagen. The outer cellular lamella consists predominantly of fibrocytes together with some fibroblasts and scattered collagen.

ISSN:1422-6405    

DOI:10.1159/000145239

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

A three-dimensional study of the sarcoplasmic reticulum (SR) of Purkinje cells of the goat heart was carried out with the use of serial thin sectioning. Two interconnected forms of SR were distinguished: myofibrillar SR and junctional SR (JSR). An extensive network of tubules lying outside as well as inside the myofibrils, constitutes the myofibrilar SR. The JSR, consists of vesicles, tubules and flattened cisternae. A three-dimensional model of a JSR cisterna was built showing its connection with both the myofibrillar SR and the sarcolemma where it forms a peripheral coupling. The potentiality and limitations of the serial-section technique for the study of the SR are discussed in comparison with other recently developed methods.

ISSN:1422-6405    

DOI:10.1159/000145240

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

In suckling mice injected intraperitoneally with mitomycin C, endotoxin, hydrocortisone and androgen, excessive proliferation of blood cells was found in the blood vessels and in the sites where neural crest cells and non-staining spindle shaped neural crest cells may be present. It is speculated that these phenomena may be related with the cell surface properties of neural crest cells in the G lphase of the cell cycle through the system mediated by cyclic AMP, and that the non-staining spindle-shaped neural crest cells in the blood vessels may be the hemopoietic stem cells.

ISSN:1422-6405    

DOI:10.1159/000145241

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The floor of the rat brain fourth ventricle has been divided into five zones to tudy the surface ultrastructure of the ependymal cells. Regional variations in the form of lense ciliation, sparse ciliation, central tufts of cilia, solitary cilia, pores, clavate and filiform αicrovilli have been observed

ISSN:1422-6405    

DOI:10.1159/000145242

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The lymphatic vessels of the ventricular conduction system, i. e. the atrioventricular (AV) node, AV bundle and bundle branches, were studied after injecting a series of 34 human and 50 canine hearts with India ink suspended in gelatin. In man, the lymphatic vessels of the AV node and the upper part of the AV bundle open into the subendocardial lymphatic network at the point of insertion of the septal cusp of the tricuspid valve; from there, the lymph is drained in part into the posterior branch of the left lymphatic trunk under the coronary sinus and in part across the membranous septum through the right atrial wall upwards into the inferior tracheobronchial nodes. The lymphatic network of the bundle branches is represented by a subendocardial network whose draining lymphatic vessels run ventrally and dorsally through the interventricular septum opening into the anterior and posterior branches of the left cardiac lymphatic collector. Anastomoses between the lymphatic vessels of the branches and those of the AV node through the AV bundle are rare. The lymphatic drainage of the conduction system of the canine ventricles is essentially similar to the lymphatic drainage encountered in man. The only difference between the two species is that in man the lymphatic vessels draining the AV node run ventrally towards the inferior tracheobronchial nodes, whereas in the dog these vessels open into the right cardiac lymphatic collector.

ISSN:1422-6405    

DOI:10.1159/000145243

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

An electromyographic study of the musculus interosseus dorsalis was performed on the right hand of 25 young adult male right-handed volunteers. The electrodes, simple coaxial needles, were implanted one at the ulnar head and the other at the radial head of the muscle. The muscles were analyzed during free movements of the index and against resistance. The same movements were done in four different positions of the forearm and hand, without variation in the results for each one of the movements. There was no significant difference between the activities of the ulnar head and radial head. During freely performed movements, muscle activity was recorded only during abduction. During movements against resistance, muscle activity was completely nil only during adduction; during the remaining movements, however, moderate (2+), strong (3+) and very strong activity (4+) was recorded.

ISSN:1422-6405    

DOI:10.1159/000145244

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

An in situ embedding technique for monolayer cultures for subsequent ultra-structural studies is described. Dehydration is carried out in graded ethanol series without propylene oxide, and Epon is used as a final embedding medium. The advantage of this method is that the plastic flask with the embedded material can be stripped off easily without affecting the monolayer culture and that the plastic does not dissolve in Epon.

ISSN:1422-6405    

DOI:10.1159/000145245

出版商:S. Karger AG    

年代:1980

数据来源: Karger